This application incorporates by reference of Taiwan application serial no. 090121387, filed Aug. 29, 2001.
1. Field of the Invention
The invention relates in general to a protection method for preventing optical disk drives from Laser leakage, and more particularly to a protection method that prevents optical disk drives from Laser leakage by means of a switch detector and an electronic detecting method.
2. Description of the Related Art
Living in today""s society where science and technology advance and change rapidly, optical disk drive has become an indispensible appliance to modern people. Among the optical disk drives available today, the Compact Disk-Read Only Memory drive (CD-ROM drive) and the Digital Versatile Disk player (DVD-ROM player) are two products which have won great popularity. For example, the users can listen to beautiful music from CD using a CD-ROM drive or watch touching movies using a DVD player which is indeed very convenient. The optical disk drives used in the abovementioned purposes are either open-top type optical disk drives or tray type optical disk drives. Both two types have an exposed pickup head. Lacking any shielding protection, it is possible that Laser rays emitted by the pickup head would leak out and thus cause harm to users which is very dangerous. In consideration of preventing Laser leakage and protecting users, an extra switch detector is added to the abovementioned optical disk drives. Laser rays will be emitted only if the top cover of an open-top optical disk drive or the tray of a tray optical disk drive are detected to be closed. Under the circumstance that the first switch detector fails to work properly, the extra one helps to reduce the possibility of mistaking the top cover of an open-top optical disk drive or the tray of a tray optical disk drive to be closed. Hereinafter, the slim type (notebook personal computer) tray optical disk drive will be used as an example with attached drawings.
Please refer FIG. 1, a top view of a tray type optical disk drive with its tray being open. In FIG. 1, the optical disk drive 100 comprises a casing 102, a motherboard 104, a control unit 106, a switch detector 108, a tray 110, a spindle motor 112 and a pickup head 114. The tray 110 is installed inside the casing 102 in a movable way, and can depart from or slide into the casing 102 according to the directions of the arrow 150 shown in FIG. 1. So the open/close status of the tray 100 allows users to displace CDs. When the optical disk drive opens its tray, i.e. the tray 110 is opened, the user can place the CD 120 on the circular disk carriage 116 of the tray 110 (for instance, along the direction of the arrow 160 shown in FIG. 1). The center point hole 122 of the CD 120 joints with the spindle motor 112 at the center point of the disk carriage 116. When the spindle motor 112 revolves, the CD 120 will be driven to revolve accordingly. The pickup head 114 is installed at the channel 118 of the tray 110 in a movable way, and moves back and forth at the channel 118 along the direction of the arrow 170 emitting Laser rays to detect whether the CD 120 has been placed on the tray 110 or not and read the data stored in the CD 120. Besides, the motherboard 104, control unit 106 and the switch detector 108 are installed inside the casing 102. Of which, the control unit 106 and switch detector 108 are installed on the motherboard 104 and are coupled with it, whereas the control unit 106 is coupled with the switch detector 108.
When the optical disk drive 100 closes its tray, the tray 110 slides towards the casing 102 along the direction of the arrow 150 shown in FIG. 1 until the switch detector 102 is touched. After having been touched by the tray 110, the switch detector 108 will send a close-status signal to the control unit 106 indicating the optical disk drive is closed. Next, the control unit 106 receives the closed-status signal and controls the pickup head 114 and the spindle motor 112 accordingly. Whether the CD 120 is placed on the tray 110 or not will be detected when the CD 120 is driven to revolve by the spindle motor 112. Having confirmed the existence of a CD, the pickup head 114 emits Laser rays and starts to read data from the CD 120. Along the direction of the arrow 170 shown in FIG. 1, the pickup head 114 moves step by step and emits Laser rays continually reading data stored in the CD 120 from inner tracks outwardly.
It is noteworthy that under normal circumstances when the tray is open, it will not touch the switch detector 108 and not any signal will be sent to the control unit 106. When the tray 108 is closed, the switch detector 108, being touched by the tray 110, will generate and send a close-status signal to the control unit 106 allowing the control unit 106 to control the pickup head 114 to emit Laser rays according to the close-status of the optical disk drive and the feedback signal of the spindle motor 112. With the tray 110 being enclosed inside the casing 102, the Laser leakage that causes harm to users can thus be prevented under the shielding protection of the casing 102 and the CD 120.
The above discussion is limited to the tray type optical disk drives only. As for the open-top optical disk drive, the discussion is as follows. The open-top optical disk drive has a structure similar to that of a tray type optical disk drive. The difference between them is that the open-top optical disk drive has a fixed tray in which a CD is accommodated with a top cover situated on top of it. When the top cover is opened, the user can place the desired CD on it; after that, the top cover is closed and the optical disk drive will be used to read the CD. Therefore, to achieve the same detecting function, i.e. detecting the close/open status of the optical disk drive and to prevent Laser leakage, the user only needs to install a switch detector in such a way that it can be initiated when the top cover closes to the casing.
However, after having been in service for a period of time, the motherboard 104 will start to experience short-circuits because of rusty circuits. The control unit 106 might mistake short-circuits for the close-status signal sent by the switch detector and continually control the pickup head to emit Laser rays. As a consequence, Laser rays will be emitted with an open and empty tray 110 resulting in Laser leakage which causes harm to users. Since the switch detector 108 is a mechanic structure, it is apt to develop aging and mechanic breakdown after having been in service for a period of time. Consequently, the switch detector 108 is likely to mistake the open-status of the tray 110 for the close-status and send the close-status signal to the control unit 106. The control unit 106 will then control the pickup head 114 to emit Laser rays according to the close-status received resulting in an open and empty tray 110 with Laser leakage which is indeed very dangerous and might cause harm to users.
In order to prevent the failure of the switch detector 108 which leads to Laser leakage, an extra switch detector is added to satisfy safety requirements. Generally speaking, an optical disk drive always uses two switch detectors to reduce the probability of errors. Apart from increase in production cost, the second switch detector, being a mechanic structure, cannot be free from aging and mechanic breakdown.
It is therefore an object of the invention to provide a protection method that prevents Laser leakage of an optical disk drive. Its electronic detecting method, which replaces the design of adding a second switch detector to a conventional optical disk drive, not only helps to reduce production cost but also effectively detects whether a CD has been placed into the optical disk drive or not, thus avoiding Laser leakage that causes harm to users.
According to the object of the invention, a protection method preventing optical disk drives from Laser rays leakage is provided. Of which, the optical disk drive is able to accommodate a CD and comprises at least a switch detector, a spindle motor and a pickup head, wherein the switch detector is used to detect the open/close status of the optical disk drive. Under normal circumstances, when the optical disk drive is closed, the switch detector will be initiated and generate a close-status signal. Whereas the spindle motor which is used to drive a CD has an empty-tray revolving speed when the optical disk drive is not loaded with any CD. When the optical disk drive has been loaded with a CD the spindle motor will have a revolving speed lesser than the empty-tray revolving speed and the pickup head will emit Laser rays to read data from CD.
The protection method first of all determines whether a close-status signal has been generated or not. If yes, then forward kick the spindle motor. Next, feed back the actual revolving speed of the spindle motor and determine whether the actual revolving speed is lesser than the empty-tray revolving speed or not: if yes, then emits Laser rays to read CD data, otherwise, performs system routine operations of the optical disk drive without emitting Laser rays.
According to the object of the invention, another protection method preventing optical disk drives from Laser rays leakage is provided. Of which, the optical disk drive is able to accommodate a CD and comprises at least a spindle motor and a pickup head, wherein the pickup head emits Laser rays to read CD data.
The protection method first of all determine whether the optical disk drive is closed or not. If yes, then forward kick the spindle motor. Next, determine whether the actual revolving speed of the spindle motor is lesser than the empty-tray revolving speed or not. If yes, then emits Laser rays to read CD data.